Electrical apparatus and contacts therefor



ELECTRICAL APPARATUS AND CONTACTS THEREFOR Filed Dec. 12, 1931 INVENTOR ATTORNEYS Patented May 5, 1936 UNITED STATES PATENT OFFICE ELECTRICAL APPARATUS AND CONTACTS THEREFOR Jacob H. Herring, Hueytown, Ala. Application December 12, 1931, Serial No. 580,715

1 Claim.

This invention relates to electrical apparatus and more particularly to the electrical apparatus wherein circuit making and breaking means are provided. Heretofore in the art many means have been devised for facilitating the making and breaking of electrical circuits in such devices, and one of these means includes spring terminal members adapted to be bridged by a contact bar of electrically conductive material.

One of the objects of the present invention is to provide an improved contact bar for electrical devices of the circuit making and breaking type including spring terminal members.

Another object of the present invention is to provide a contact bar element which is resistant to frictional wear.

Another object of the present invention is to improve the wear resistance of terminal members of the spring contact type.

Other objects and advantages will be apparent as the invention is more fully hereinafter disclosed.

In accordance with the objects of the present invention I provide in electrical devices of the circuit make and break type including spring terminal members, a rotatable contacting element therefore whereby a rolling contact between the contactor bar and spring terminal members is obtained in place of the usual sliding and frictional contact heretofore obtained between these elements.

Before further disclosing the present invention reference should be made to the accompanying drawing wherein:

Fig. 1 is a front elevational view of an electrical device known in the art as a switch interlock device of. the magnetic contactor type, incorporating the rotatable contact element of the present invention;

Fig. 2 is a side elevation of the same;

Fig. 3 is an enlarged sectional view taken along plane 3-3, Fig. 1;

Fig. 4 is an enlarged sectional view taken along plane 4-4, Fig. 2;

Fig. 5 is an enlarged perspective view illustrating one of the features of the present invention.

The electrical device illustrated in the drawing and incorporating the frictionless contactor element of the present invention is known in the art as a magnetic contactor device. The device is mounted upon a panel I and comprises essentially terminals 2--2 connected through the panel I to electric current supply wires 3, terminals 4-4 connected through the panel to electric current supply wires 5 and contactors 8 and 9 adapted by fulcrumed switch elements Il-H and Ill-l0 pivoted about an axis 16 to be alternatively connected across the terminals 2--2 and 44 respectively. Electromagnetic means in- 5 eluding magnet 6 and coil I is provided to effect the alternative engagement of contactors 8 and 9 with terminals 2-2 and 44 respectively. Magnetic coil 1 is adapted to be energized by a, push button controlled circuit of any desired type 10 (not shown), to effect the engagement of contact elements 8 and 9 across terminals 2-2 and 44 respectively. The electromagnetic means acts through switch element 12 against spring tension means or gravity means utilized to retain 15 the contact bar across one set of terminals 2-2 and 4-4 to position the other contact elements 8 or 9 in a terminal closing position. A cushioning stop (not shown) or other means is provided to stop the contact bar 9 in its proper 20 relation to terminals 4-4 as it makes contact with said terminals.

Heretofore contact element 9 has been comprised of a round rod fixedly positioned upon and electrically insulated from arms IBI0 of 2 the fulcrumed lever. Under repeated use the surfaces of contact 9 and of spring clip terminals 44 are worn away to such an extent that repeated replacement of the spring terminals 4-4 is necessary. Contact 9 also must be repeatedly 30 turned about its axis to present new surfaces for frictional engagement with spring terminals 4-4 and frequently must be replaced.

By the practice of the present invention this difficulty is substantially eliminated throughout 35 a prolonged operating life by comprising contact element 9 of a rotatable element whereby instead of obtaining frictional engagement between bar 9 and spring clip terminals 4-4 I obtain a rolling contact substantially free from frictional wear.

The specific type of rolling contact which I may obtain may be Widely varied but preferably should be adjustable in type and replaceable in 45 nature as is illustrated in detail in Fig. 4.

In Fig. 4 I have illustrated this preferred type and element 9 is comprised of three parts, a center contacting element 9 which is substantially a round or tubular bar comprised of electrically 50 conductive material and two bearing elements |3-l3 adapted to be rigidly held in the ends of arm l9 substantially as shown and electrically insulated therefrom by insulating bushings l4. Element 9 is rotatable in bearing l5. Bearing 55 I may be a simple bearing as illustrated or may be ball-bearing or roller bearing, if desired.

In this arrangement of elements when the contactor 9 contacts with spring terminals 44 in the manner indicated in Fig. 3 it is believed clear that the contactor rotates about its longitudinal axis in bearings l5-|5 and that no frictional engagement of the contacting surfaces is obtained. A prolonged useful operating life is thereby obtained.

While I have shown as a specific embodiment I a three element contactor 9 it is obvious that a single element may be employed if desired provided suitable bearing recesses be provided therefor in arms Ill-40. While I have also disclosed the application of the same to an electrical device of the magnetic contactor type, I am not to be limited thereby as therotatable contact element of the present invention is adapted to application in a plurality of electrical apparatus.

From the above description and accompanying drawing it is believed clear that many modifications and adaptations of the present invention may be made but such modifications and adaptations as may fall within the scope of the accompanying claim are anticipated.

What I claim is:

A circuit make and break means for electrical devices comprising in combination a pair 01' spaced spring terminals, a contact bar comprised of a cylindrical electrically conducting member and a pair of end supporting members therefor, each of said end members being provided with a .bearing recess adapted to rotatably receive the end of the said electrically conducting member, and means to pivotally support said bar whereby the same may be moved into and out of rolling wiping engagement across said terminals, said means comprising parallel spaced arms pivotally supported on opposite sides of said terminals, means to secure one of said end sections to each of said arms with the said cylindrical member supported therebetween in said bearing recesses in a position to bridge said terminals in one pivoted position of said arms, said means providing the electrical insulating of the said end section from the arm and for the adjustment of said end sections along the longitudinal axis of 7 said center section to permit ready removal and replacement of said cylindrical member.

JACOB H. HERRING. 

